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INSTALLATION
MANUAL
(800) 7Bostik / (800) 726-7845
Please be aware that local codes may require this product and/or the
control to be installed or connected by an electrician. Please leave this manual with the end user.
2
Bostik HeatStep™ Mat Installation Manual
You are required to thoroughly read all installation instructions and product safety information before beginning the installation
of this product. FAILURE TO COMPLY WITH PROPER INSTALLATION AND MAINTENANCE INSTRUCTIONS COULD RESULT IN
PROPERTY DAMAGE, PERSONAL INJURY AND/OR DEATH. Bostik is not responsible for damages resulting from improper
installation and/or maintenance.
Welcome to HeatStep™!
HeatStep™ floor heating mats are a simple way to heat an indoor space. This instruction manual is provided as a guide
to installing HeatStep™ Mats, including design considerations, installation steps, limitations, precautions, and floor
covering guidelines.
Specifications for HeatStep™ Mat:
HeatStep™ Mat is a complete heating mat consisting of
a series heating wire and a power lead for connection to the
electric power supply. The heating wire length cannot be
cut to fit.
Controls: HeatStep™ Mats must be controlled by a
HeatStep™ floor sensing thermostat.
Voltage: 120 VAC, 240 VAC, 1-phase (see Table 2)
Watts: 12 W/sqft (41 Btu/h/sqft)
Mat Mesh
Maximum circuit load: 15 A
Factory Splice
Maximum circuit overload protection: 20 A breaker
Power lead
GFCI: (Ground Fault Circuit Interrupter) required for
Heating Wire
each circuit (included in the HeatStep™ control)
Listing: UL Listed for U.S. and Canada under UL 1693
and CAN/CSA C22.2 No. 130.2-93, File No. E185866
Application: Indoor floor heating only (-X on the nameplate label indicates CUL Listing for this application). Suitable for
installation in a shower area (see Step 4.10 for restrictions). (-W on the nameplate label indicates CUL Listing for Wet
Location in Canada per Canadian Electrical Code, Part I (CEC). Embedded in polymer-modified cement based mortar only
(see Phase 5).
Minimum bend radius: 1 inch
Maximum exposure temperature: (Continuous and storage) 194ºF (90ºC)
Minimum installation temperature: 50ºF (10ºC)
Skill Level
Installation must be performed by qualified persons, in accordance with local codes, ANSI/NFPA 70 (NEC Article 424) and CEC
Part 1 Section 62 where applicable.
Prior to installation please consult the local codes in order to understand what is acceptable. To the extent this information is
not consistent with local codes, the local codes should be followed. However, electrical wiring is required from a circuit breaker
or other electrical circuit to the control. It is recommended that an electrician perform these installation steps. Please be aware
local codes may require this product and/or the control to be installed by an electrician.
xpected floor temperature
E
Heating performance is never guaranteed. HeatStep™ Mat is designed to deliver 12 W/sq.ft. The floor temperature
attainable is dependent on how well the floor is insulated, the temperature of the floor before start up, and the overall thermal
drain of the floor mass. Insulation is required for best performance. Refer to Phase 5 for important design considerations.
These are the three most common installa­tions:
1. Wood framing: With the mat installed on a well-insulated wood
subfloor, and thin-set mortar and tile on top, most floors can be heated up
to 20°F warmer than they would otherwise be.
2. Insulated concrete slab: With the mat installed on an insulated
concrete slab, and thin-set mortar and tile on top, most floors can be
heated up to perhaps 15°F warmer than they would otherwise be.
3. Uninsulated concrete slab: With the mat installed on an uninsulated
concrete slab, and thin-set mortar and tile on top, most floors can be
heated up to perhaps 10°–15°F warmer than they would otherwise be.
Please consult a designer or the factory if questions remain about
the surface tempera­ture that can be expected from the cables in any
particular construction.
Table of Contents
Phase 1
Designing the System. . . . . . . pg 4
Phase 2
Preparations. . . . . . . . . . . . . . . . pg 5
Phase 3
Electrical Rough-in. . . . . . . . . . pg 8
Phase 4
HeatStep™ Mat Installation. . pg 9
Phase 5
Floor Coverings. . . . . . . . . . . . . pg 13
Phase 6 Control Installation. . . . . . . . . . pg 15
Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg 16
Control Wiring. . . . . . . . . . . . . . . . . . . . . . . . . . . pg 19
Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg 21
Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . pg 22
Bostik HeatStep™ Mat Installation Manual
Table 1
CAUTIONS!
R e a d B e f or e I nsta l l in g H e at S t e p ™ M at
As with any electrical product, care should be taken
to guard against the potential risk of fire, electric
shock, and injury to persons. The following cautions
must be observed:
NEVER install HeatStep™ Mat under carpet, wood,
vinyl, or other non-masonry flooring without
embedding it in Bostik SL-150™, WebCrete® 95,
WebCrete® 98 or Ultra Finish™.
NEVER remove the nameplate label from
the power leads. Make sure it is viewable for inspection later.
NEVER extend the heating wire beyond the room or
area in which it originates.
NEVER allow a power lead or sensor wire to cross over
or under a heating cable. Damage could result.
NEVER install HeatStep™ Mat in adhesives or glues
intended for vinyl tile or other laminate flooring,
or in pre-mix mortars. It must be embedded in
polymer-modified, cement based mortar.
NEVER cut the heating wire. Doing so will cause
dangerous overheating and will void the warranty.
The power lead may be cut shorter if necessary, but
never remove completely from the heating wire.
NEVER bang a trowel or other tool on the heating
wire. Be careful not to nick, cut, or pinch the wire
causing it to be damaged.
NEVER use nails, staples, or similar to fasten the
heating wire to the floor.
NEVER attempt to repair a damaged heating wire,
splice, or power lead using unauthorized parts. Use
only factory authorized repair parts and methods.
NEVER splice one mat heating wire to another mat
heating wire to make a longer mat. Multiple mat
power leads must be connected in parallel in a
junction box or to the thermostat.
NEVER install one mat on top of another or overlap
the heating wire on itself. This will cause
dangerous overheating.
NEVER forget to install the floor sensor included with
the thermostat.
NEVER install HeatStep™ Mat in any walls, or over
walls or partitions that extend to the ceiling.
NEVER install mats under cabinets or other builtins having no floor clearance, or in small closets.
Excessive heat will build up in these confined
spaces, and the mat can be damaged by fasteners
(nails, screws, etc.) used to install built-ins.
ALWAYS completely embed the heating wire and
factory splices in Bostik SL-150™, WebCrete® 95,
WebCrete® 98 or Ultra Finish™.
ALWAYS maintain a minimum of 2” spacing between
heating wires.
ALWAYS pay close attention to voltage and amperage
requirements of the breaker, the thermostat, and
the HeatStep™ Mat. For instance, do not supply 240
VAC power to 120 VAC mat as damage will result.
ALWAYS make sure all electrical work is done by
qualified persons in accordance with local building
and electrical codes, Section 62 of the Canadian
Electrical Code (CEC) Part I, and the National
Electrical Code (NEC), especially Article 424.
ALWAYS use copper only as supply conductors to the
thermostat. Do not use aluminum.
ALWAYS seek help if a problem arises. If ever in
doubt about the correct installation procedure to
follow, or if the product appears to be damaged, the
factory must be called before proceeding with the
installation.
Installation must be performed by qualified personnel,
in accordance with local codes and standards. A licensed
electrician is recommended. Read these important warnings and all installation instructions prior to
installation. Failure to do so can result in fire, shock,
property damage, personal injury, and/or death.
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Bostik HeatStep™ Mat Installation Manual
Phase 1: Designing the System
• T he heating wire and factory splices must be completely
embedded in the thin-set. Only the power lead may
exit the thin-set and enter the wall. Pull power leads
through UL Listed conduit to a UL Listed junction box or
the control box.
HeatStep™ Mat should be installed in all interior floor areas
intending to be warmed. It cannot be used for exterior
applications, snow melting, in or on walls, or in ceilings. In many
applications it can be used to heat the room but an accurate
heat-loss calculation must be made to determine if enough heat STEP 1.2
will be provided to match the heat loss.
Multiply the heated area square footage calculated in Step 1.1
by 0.90 to allow 4" to 6" spacing around the edges of the floor
STEP 1.1
area. Use this resulting square footage to select the appropriate
Make a sketch of the room and measure the overall room size. mats from Table 2 on page 5.
Measurement should be made from wall-to-wall and include
size and location of cabinets, tub, toilets, etc. Determine
Remember:
the total square footage of floor area to be warmed by
subtracting out the area associated with the built-ins. Keep in • Do not exceed 15 amps at 120 VAC (1800 watts) or
mind the following:
15 amps (3600 watts) at 240 VAC through a single HeatStep™
control or HeatStep™ Relay.
• Heat will not radiate beyond about 1-1/2" on either
side of the heating wire, therefore consistent coverage
• Select either 120 VAC or 240 VAC depending on the power
is important.
available. DO NOT mix voltages on the same HeatStep™
• Do install heating wire within about 1-1/2” to 2” from a
control if more than one mat is to be installed to cover an
counter or vanity in the kick-space to ensure warmth in
area.
this area.
• Load no more than 12 amps on a 15-amp circuit breaker, or
15 amps on a 20-amp circuit breaker.
• Do not install the heating wire underneath cabinets or
fixtures having no floor clearance or inside a wall. Excessive
• If the area requires more than 15 amps to be controlled by
heat will build up and cause damage.
one thermostat use HeatStep™ Relays to take the additional
• Do not run the heating wire into small closets or other
amp load.
confined areas where excessive heat will build up.
• Do not install the heating wires closer than 6" from toilet
• See the Wiring Diagrams in Appendix for further information.
rings to avoid possible melting of wax rings.
• Do not directly cross expansion joints.
If the exact size of product calculated is not found in the
• Do not place the heating wire any closer than 4" from other selection Table 2 on page 5, it may be necessary to adjust the
items such as forced air ducting or potable piping to avoid warming area(s) or select the next smaller size. Remember, the
overheating them.
heating wire must never be cut shorter to fit, and must be
• HeatStep™ Mat must be laid in a manner to prevent surface completely embedded in thin-set, thick-set, or self-leveling
obstructions being placed directly over the mat location.
mortar. Failure to do so may result in damage to the
Failure to do so will result in capturing heat and may allow
product. Do not select a product larger than necessary.
potential damage from mounting brackets, bolts, or similar
penetrations associated with pedestals, support columns,
walls, or similar.
• Install the heating wires 4" to 6" away from the perimeter
walls of the room. Make sure the heating wire will not be
located underneath finish trim.
Kitchen Design
Refrigerator
Sink
Cabinets
1. Heated area = total area –­ built-in areas.
2. Multiply heated area x 0.90
3. Select Appropriate product size
Bostik HeatStep™ Mat Installation Manual
Make sure proper subfloor materials are selected in accordance
with the construction and floor covering requirements. Use of
a moisture barrier, an anti-fracture membrane, backerboard, or
other materials are recommended when installing tile or other
stone floor covering.
STEP 1.4
Pay careful attention to the total amps when selecting
multiple mats to make sure the controls, circuit breaker
panel, and all wiring have the proper capacity. Design circuit
protection and wiring to handle 125% of total amp load.
Phase 2: Preparations
Before installing HeatStep™ Mat, make sure to fully inspect the
products and carefully plan the site.
Items Needed
Materials:
- HeatStep™ thermostat control with floor sensor. The
HeatStep™ control is listed separately from the HeatStep™
Mat.
- 20-amp circuit breaker
-UL Listed electrical box (extra deep) for the control;
single-gang (not a gangable type) for one or two mats or
4"-square deep box with a single-gang "mud ring" cover
- 4" junction box with a cover (if needed)
- Flexible or rigid UL Listed conduit (for new construction)
- 12-gauge or 14-gauge electrical wiring cable
(consult local code)
- Wire nuts if using an additional junction box
- Nail plate
Tools:
- Digital multi-meter for ohms testing;
must read up to 20,000 ohms to measure sensor
- Drill with 1/2" & 3/4" bits
- Hammer and chisel
- Wire strippers
- Phillips screwdriver
- Fish tape
- Hole saw
- Floor covering installation tools
Table 2 (HeatStep™ Mat sizes)
120 VAC
2 ft Wide
STEP 1.3
5
Mat Square
Footage
Mat Size
(W x L)
Model
Number
Amp
Draw
Ohms
30
2' x 15'
K640115
3.0
34 - 42
40
2' x 20'
K640120
4.0
25 - 32
50
2' x 25'
K640125
5.0
20 - 26
60
2' x 30'
K640130
6.0
17 - 21
70
2' x 35'
K640135
7.0
14 - 18
Note: Other HeatStep™ Mat sizes avialable in both 120 VAC and
240 VAC upon request.
It is important to select the proper sized HeatStep™ Mat for the given
area. HeatStep™ Mat can not be cut shorter in order to fit a given area.
Doing so will damage the heating wire and will prevent the system
from working.
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Bostik HeatStep™ Mat Installation Manual
INSPECT MAT, CONTROL, and SENSOR
C
AUTION: Make sure power is not applied to the
product until it is fully installed and ready for final
testing. All work must be done with power turned
off to the circuit being worked on.
Ground Lead
White or Blue Lead
Black Lead
Black wire to COM
Red wire to Ω
STEP 2.1
Remove the Mat, HeatStep™ control, and HeatStep™ sensor
from their packages. Inspect them for any visible damage
and verify everything is the correct size and type according
to the plan and the order. Do not attempt to install a
damaged product.
200 ohm setting
Ground Lead
STEP 2.2
White or Blue Lead
Record the product information in Table 4. Give this
information to the homeowner to keep in a safe place.
Black Lead
The HeatStep™ Mat model number, serial number, voltage,
and resistance range are shown on a nameplate label
attached to the power leads, as well as the marking "(x)-FOR
INDOOR FLOOR HEATING APPLICATIONS".
Do not remove this nameplate label. The electrical
inspector will need to see this.
Record the information from the
nameplate label into the
HeatStep™ Mat and Sensor
Resistance Log. Leave the
nameplate label attached to the
power leads for later inspection.
STEP 2.3
Use a digital multi-meter set to the 200Ω or 2000Ω (2kΩ)
range to measure the resistance between the conductors
of the mat power leads. Record these resistances in Table 4
under “Out of the box before installation”.
The resistance should measure within the resistance range
on the nameplate label. If it is a little low, it may be due
to low air temperatures or meter calibration. Consult the
factory if in doubt.
Ground Lead
White or Blue Lead
Black Lead
Press the test lead tips to the Black and White (or Blue for 240 VAC) power lead wires.
This reading should correspond to the factory resistance range on the nameplate label
attached to the Power lead.
Readings between the Black and Ground and the White (or Blue for 240 VAC) and
Ground power lead wires should measure “open”, or “O.L”, or the same as displayed when
the test leads are not touching anything.
Bostik HeatStep™ Mat Installation Manual
Measure the resistance between either of the white or
black leads and ground lead. This measurement should be
“open”, usually indicated by an “OL” or a “I”. This is the same as
displayed when the test leads are not touching anything.
If there is any change in the reading, record this information
and contact the factory before continuing. This could
indicate damage, test lead problems, or a number of other
issues. Try “pinning” the test leads to the cable lead wires
against a hard non-metal surface if the readings continue to
fluctuate.
Change the meter to the 20,000 ohms (20 kΩ) range.
Measure between the lead wires of the HeatStep™ sensor.
This resistance varies according to the temperature sensed.
Table 3 provides approximate resistance-to-temperature
values for reference.
Table 3 (floor sensor resistance values)
Temperature
55°F (13°C)
65°F (18°C)
75°F (24°C)
85°F (29°C)
Typical Values
17,000 ohms
13,000 ohms
10,000 ohms
8,000 ohms
The Wire Fault Detector will constantly monitor the heating wire during
the entire installation process. If the wire is cut or damaged during
installation, the Wire Fault Detector will sound an audible alarm.
Table 4 - HeatStep™ Mat Resistance Log
Mat 1
Mat 2
Mat 3
Mat serial number
Mat model number
Mat voltage
Mat resistance range
Sensor
OUT OF THE BOX BEFORE INSTALLATION
Mat white to black
Mat white to ground
Mat black to ground
Sensor
AFTER MAT IS SECURED IN PLACE
Mat white to black
Mat white to ground
Mat black to ground
Sensor
AFTER FLOOR COVERINGS ARE INSTALLED
Mat white to black
Mat white to ground
Mat black to ground
Sensor
Retain this log to retain the warranty! Do not discard!
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Bostik HeatStep™ Mat Installation Manual
Phase 3: Electrical Rough-in
STEP 3.2: 
Install Electrical Boxes
STEP 3.1: 
Circuit Breaker (Overcurrent Protection)
HeatStep™ Thermostat:
Install an extra-deep electrical box for the HeatStep™
thermostat. Follow the instructions included with the
HeatStep™ control for complete information on location and
wiring.
HeatStep™ Mat(s) must be protected against overload
by a circuit breaker. GFCI type (ground fault circuit interrupter)
or AFCI type (arc-fault circuit interrupter) breakers may be
used if desired, but are not necessary.
The rating of the breaker (see Table 5) is determined by
the amp draw of the heating mats (see Table 2 or the
Nameplate Label). If multiple mats are to be controlled by one
HeatStep™ control, total their amp draws. If this total exceeds
15 amps, an additional breaker and control will be required.
The total amps on each breaker can not exceed 15 amps. Do
not use breakers rated over 20 amps.
Table 5
Circuit Breakers and Supply Wire
Mat(s)
Supply Wire
Breaker
VAC
total amps
(AWG)*
qty type**
rating
120 up to 12 amps
14
1
SP
15 or 20 A
120 up to 15 amps
12
1
SP
20 A
240 up to 12 amps
14
1
DP
15 or 20 A
240 up to 15 amps
12
1
DP
20 A
* Recommended only. Follow local codes for wire gauge size.
** SP= single-pole, DP=double-pole
HeatStep™ Relay:
Install an extra-deep electrical box for any HeatStep™
Relay(s). The HeatStep™ Relay is used when more than 15
amps must be controlled by one HeatStep™ thermostat.
Follow the instructions included with the HeatStep™ Relay
for complete information on location and wiring.
Junction Boxes:
If a mat is to be located so its Power lead is not long enough
to reach the HeatStep™ control or HeatStep™ Relay directly,
a junction box must be installed. Do not attempt to make a
connection to other wiring without a junction box. Use a
standard junction box with a cover, mounting it below the
subfloor, in the attic, in the wall, or in another location
easily accessible after all coverings are complete. If the
HeatStep™ control sensor wire is not long enough to reach
the HeatStep™ control directly, it may be extended. A junction box may be required by local code to make this connection. Follow the installation instructions included with
the HeatStep™ control for details.
For construction with an existing wall or where the wall is
covered, cut the necessary openings to mount the electrical
boxes listed above. Wait to install the boxes until all wiring is
fed into these locations to make it easier to pull the wire.
It may be possible to tap into an existing circuit as long as
there is adequate capacity for the mat(s) and any additional
appliance, such as a hair dryer or vacuum cleaner. Avoid
circuits which have lighting, motors, exhaust fans, or hot tub
pumps due to possible interference.
!
WARNING
To prevent the risk of personal injury and/or death, do not
perform any electrical work unless qualified to do so. Work
should be done with great care and with power turned off
to the circuit being worked on. Follow all local building
and electrical codes.
Install an extra-deep single-gang box if
connecting one or two cables to the control.
Use a 4"-square deep box with a singlegang mud ring cover if connecting three
cables, because the extra room is needed
for the wire, wire nuts, and control.
Bostik HeatStep™ Mat Installation Manual
9
STEP 3.3: Bottom Plate Work
Drill or chisel holes at the bottom plate as indicated. One hole
is for routing the power lead conduit and the other is for the
thermostat sensor. These holes should be directly below the
electrical box(es).
STEP 3.4: 
I nstall Power Lead Conduit and Thermostat Sensor
Power Lead Conduit:
The shielded power lead can be installed with or without
electrical conduit (recommended for added protection
against nails or screws) depending on code requirements.
Remove one of the knock-outs in the electrical box to route
the power lead. If electrical conduit is not required by code,
install a wire collar to secure the power leads where they
enter the box. If conduit is required by code, install 1/2"
(minimum) conduit from the bottom plate up to the
electrical box. For multiple power leads (multiple mats)
install 3/4" conduit.
Power lead
conduit
Wire Clip
Sensor wire
Power lead
Thermostat Sensor:
The HeatStep™ control sensor can be installed with or withConduit enclosing power lead.
out electrical conduit depending on code requirements.
Conduit is recommended for added protection against nails
or screws. Do not place the sensor in the same conduit as
the power leads to avoid possible interference. Open a separate knock-out in the bottom of the thermostat box. Feed
the sensor (and conduit, if used) through the knock-out,
down through the cut-out in the bottom plate, and out into
the floor where the heating mat will be installed. If the sensor wire needs to be secured to the wall stud, wait until after
the mat and sensor are completely installed on the floor.
Sensor wire
If going in to an existing
wall, cut out dry wall and
chisel out bottom plate to
route wires to control.
STEP 3.5: 
Rough-in Wiring
Install appropriate 12 or 14 AWG electrical wire from the circuit breaker or branch circuit source to the HeatStep™ control
electrical box (and HeatStep™ Relay box(es) if needed) following all codes, see Table 5.
If HeatStep™ Relay(s) are used, feed appropriate wire (see
HeatStep™ Relay installation manual for size and type)
between the HeatStep™ Relay(s) and the HeatStep™ control.
Phase 4: Mat Installation
STEP 4.1:
Floor Cleaning
The floor must be completely swept of all debris including
all nails, dirt, wood, and other construction debris. Make
absolutely sure there are no objects on the floor which might
damage the Mat wire.
Follow instructions for subfloor prep for Bostik SL-150™,
WebCrete® 95, WebCrete® 98 or Ultra Finish™.
STEP 4.2:
Material
Make sure all of the correct materials have been purchased.
A general list of materials is found at the beginning of
this manual.
Verify the amount of mat supplied is the proper size for the
area to be heated before beginning the installation. Verify
thermostat location.
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Bostik HeatStep™ Mat Installation Manual
STEP 4.3:
Position the Power Leads
Carefully cut the tie binding the power lead coil. Do not nick
the braid covering the power lead.
Table 6:
Mat Turns and “Fill-in” Techniques
This table contains some of the common turns and techniques
used to layout around corners, angles, and built-ins.
Place the mat on the floor to ensure the power lead will reach
the HeatStep™ control electrical box or junction box location.
If the power lead will need to cross a long distance to reach
the control location, it may be possible to cut the mat mesh
and pull loose the length of heating wire needed.
Make sure the power lead factory splice is to be
completely flat and in the floor mortar, not in the wall.
STEP 4.4:
Test Fit the Mat
t
Cu
at
at
m
m
t
Cu
Roll out the mat, flipping it as needed to cover the intended
area. This is very important to ensure proper fit before
proceeding. If there is too much mat for the area it cannot
be cut shorter and heating wire cannot be routed into a wall,
under baseboards, or other similar areas. All heating wire
must be embedded in the floor mortar.
CAUTION: Do not cut the heating wire to make it fit
the area. Doing so will cause dangerous overheating
and will void the warranty.
Carefully cut the white mesh to make turns. Never cut, nick, or otherwise damage the
heating wire.
Rotate
Flip mat
over
180° or Back-to-Back Turn.
Cu
t
ma
t
90° or Flip Turn.
Use hot glue to
attach wire to the floor.
M
remat m
ov esh
ed
Roll
over
Roll-over Turn.
Fill-in Technique.
Installing in front of cabinets and toilets:
Install the mat approximately 4"–6" away from walls, showers,
tubs, drains, etc. and 6” from a toilet wax ring. Install in-line
with vanity and counter areas. Install roughly 20" from back
wall in toilet area.
DO NOT leave gaps between the mats. The heat will conduct only about 1-1/2" from the heating wire. Mat should be
installed continuously across the floor. Never install mats in
a fashion causing the heating wires to be any closer than 2"
from each other or to overlap.
To warm the maximum amount of floor area, it may be
necessary to make the mat(s) fit odd-shaped spaces, fit
into corners, and work around angles and built-ins. See
Table 6 for technique examples and the Appendix for full
layouts, additional techniques, and cautions.
Install mat right up to the face of the
cabinet as shown above.
Mat can be installed under tile to
within 6" from the wax ring, and can
slightly underlay the foot of the toilet
if need be (approximately 20" from
wall).
Bostik HeatStep™ Mat Installation Manual
11
STEP 4.5:
Secure the Mat to the Floor
After test-fitting the mat and deciding what technique
will be used to help fill any odd spaces, carefully cut the mesh
where needed.
Lay the mat down flat. Ensure it fits well and has no folds or
large ripples.
IMPORTANT: S
ecuring the mat as flat as possible will help
make a smooth surface for spreading mortar.
Secure the mat to the flooring using the double-sided tape
supplied in the installation kit. Apply a length of the tape to
the floor at each end of the mat and every 12” to 24” (30 cm
to 60 cm).
If an area of mesh does not lay flat enough, use hot-glue, or
pneumatically applied staples to help. This may be necessary
at the ends of the mat. If staples are used, 3/8" x 1/4" chisel
type are recommended. Do not staple closer than 1/4" (7 mm)
from the heating wire. Be very careful not to damage the
heating wire.
DO NOT staple or apply tape over the heating wire. Damage
can result.
DO NOT u
se nails, duct tape, other types of tape, or other
unapproved fasteners to hold the heating wire or
mesh in place. Damage can result.
STEP 4.6
Use a digital multi-meter to measure the resistance between
the conductors of the power leads again. Record these
resistances in Table 4 under “After mat is secured in place”.
STEP 4.7
Connect the Wire Fault Detector to the mat power lead.
If multiple mats are used, connect them to the Wire fault
detector in series (white-to-black). Only one white, black, and
ground lead should be connected to the Wire fault detector.
Refer to the Appendix for Wire fault detector wiring diagrams.
STEP 4.8
Nail
Plate
Feed the power leads through the conduit to the control
electrical box, leaving at least 6"-8" of free power lead. Chisel
a slot in the floor to recess the factory splice level with the
heating wire. Secure the factory splice with hot glue so it
cannot be pulled into the conduit.
It may be necessary to use a metal nail plate to protect the
power lead and sensor wire as they transition into the wall.
This will help prevent nail penetrations from drywall and
baseboards trim.
STEP 4.9
Feed the sensor wire through the sensor conduit, leaving
at least 6"-8" of free lead length at the control electrical
box. Weave the sensor at least 1' into the mat area, halfway
between the heating wires, and secure it using hot glue. Do
Floor
Sensor
Power Lead/
Heating Wire
Connection
Chisel a path for the power lead and factory splice. Use hot glue
to secure to the floor. Place a metal nail plate over the transition
point to protect the power lead and sensor wire.
12
Bostik HeatStep™ Mat Installation Manual
not cross the heating wires. It may be necessary to chisel a
small section of the subfloor to accommodate the sensor,
depending on the thin-set thickness being used.
Conduit
Power Lead
Factory Splice
(in thin-set, not in conduit)
STEP 4.10:
Shower Application
Note: Acceptance of this application must be verified
by the local inspector or authority having
jurisdiction (AHJ).
1. Refer to diagrams in the Appendix, especially page 17.
2. Never install Mat in shower walls (or any
other wall).
3. Never make a field splice to mats installed in a shower.
Sensor
4. Use the double-sided tape or hot-glue to secure the mat.
Do not use staples or anything that will damage any
waterproofing membrane.
Tape
Heating Wire
Top-Down view of HeatStep™ Mat and the sensor
entering wall.
5. Make a 1” wide notch in the curb to embed the heating
Bostik HeatStep™ Mat Installation Manual
wire. Ensure the wire is not pinched or bent sharply. Do
not run the heating wire through a non-masonry curb,
causing it to overheat.
Locate power lead and factory connection to heating wire at least
1’ outside the shower area.
Tile
Thin-set Mortar
Shower Curb
Heating Wire
Notches in Shower Curb
(Minimum 1” wide, to avoid sharp
is
bends in cable and ensure cable
fully embedded in mortar.)
Factory Splice
6. Embed mats in mortar and install only under tile,
stone, brick, or other masonry surface, per this
instruction manual.
7. Never begin the mat in a shower. The connection
between the power lead and the heating wire must
be fully embedded in mortar and located at least
1' (304.8 mm) away from shower openings and other
areas normally exposed to water.
8. Mat controls must be located at least 4' away from
shower openings. Controls cannot be exposed to water
or touched by a person while in the shower area.
9. All grout seams should be sealed after the mortar and
grout has completely cured.
10. As an option, consider installing a dedicated mat in
the shower area, separate from the rest of the floor.
This will increase control options, allowing less floor to
be warmed when the shower is not required. It will
also allow for better isolation of the shower area in the
off-chance a problem occurs.
STEP 4.11
Take photographs of the mat installation. This can be very
useful later during remodel work to help avoid possible
wire damage. Keep the photos with this installation
manual and provide to end user upon completion.
Phase 5: Floor Coverings
It is recommended to consult with professional flooring
installers to make sure proper materials are used and
proper installation techniques are followed. Please note, this
installation manual is not a structural or a floor covering
installation manual and is intended only for general guidance
as it applies to the HeatStep™ Mat product.
13
When installing tile or stone, the Tile Council of North
America (TCNA) guidelines, National Tile Contractors
Association (NTCA), or ANSI specifications should be followed as a minimum standard.
Use Bostik SL-150™, WebCrete® 95, WebCrete® 98 or Ultra
Finish™. Do not use water-based multi-purpose materials
when installing a radiant product.
Do not use solvent based adhesives or pre-mix mortars
because they are not as heat resistant and do not conduct
heat well.
Select the proper size trowel for the installation of tile or
stone. We recommend a minimum 3/8” x 1/4” trowel. This
trowel works well for most ceramic tile. A thicker thin-set
can be used if required. Select the thin-set thickness in
accordance with the floor covering requirements.
For additional information on tile installation, please
contact TCNA at 864-646-8453 or visit their web site
at www.tileusa.com, or contact NTCA at 601-939-2071 or
see their web site at www.tile-assn.com
When installing floor coverings other than tile or stone,
follow industry and/or manufacturer’s recommendations.
Ensure the mat is first covered with a layer of SL-150™ selfleveling cement based mortar, letting it cure fully before
applying any surface underlayment, floating wood or
laminate flooring, carpet, etc. The combined R-values of all
floor coverings over the mat should not exceed R-3. Higher
R-values will diminish performance. Consult the floor covering manufacturer to verify compatibility with radiant electric
heat. Also, make sure nails, screws, or other fasteners do not
penetrate the floor in the HeatStep™ Mat area. The wire can
easily be damaged by fasteners penetrating the floor.
All floor coverings must be in direct contact with the
cement-based mortar encasing the mat. Do not elevate the
floor above the mortar mass. Do not install 2” x 4” wooden
nailers (sleepers) on top of a slab for the purpose of attaching hardwood. Any air gap between the heating mat and
the finished floor covering will drastically reduce the overall
output of the heated floor.
Care should be taken when laying area rugs, throw rugs,
and other surface products on the floor. Most products are
okay to use, but if in doubt, consult the product manufacturer for compatibility. Do not use rubber backed products
that may degrade or very heavy rugs that will trap heat. Be
careful not to place a rug over the area where the sensor tip
was placed, causing false thermostat readings.
When placing furniture make sure an air clearance of at
least 1-1/2” is available. Furniture able to trap heat can damage the heating system, the flooring, and the furniture over
time.
Use a digital multi-meter to measure the resistance
between the conductors of the power leads again.
Record these resistances in Table 4 under “After floor
coverings are installed”.
14
Bostik HeatStep™ Mat Installation Manual
DOUBLE-PLYWOOD over fRAME fLOOR
Type of Construction
Mortar Applications:
Thin-set and thick-set (self-leveling) mortar
applications are illustrated to the right.
a. If a backer board or plywood sheeting is
used to strengthen the floor, or if the mat
will be placed directly onto the slab, install
mat in the thin-set mortar bond coat above
these materials.
b. If a thicker mortar bed, or self-leveling concrete, is used to strengthen the floor, mat
can be installed in either the mortar bed
(dry-set) or in the mortar bond coat directly
below the tile or stone.
HeatStep™ Mat is generally installed above the
self-leveling mortar in a thin-set bond coat.
Use plastic lath instead of the typical metal
lath when installing in a self-leveling layer.
Self-leveling Mortar Applications:
These are appropriate applications if installing
engineered wood, vinyl, laminate, or carpet
floor coverings. Attach the mat to the subfloor
or slab, then pour self-leveling mortar 3/8" to
1/2" thick. Install floor covering after the mortar has cured.
Tile/stone or
laminate flooring
Cementitious Underlayment
SL-150™, WebCrete® 95,
WebCrete® 98 or Ultra Finish™
HeatStep™ Mat
Underlayment Grade Plywood
Main Plywood Subfloor
Insulation (per International
Residential Code, Chapter 11)
CEMENT BACKERBOARD OVER FRAME FLOOR
Tile/stone or
laminate flooring
Bostik Thin-set
Special Precautions
Isolation Membrane: Install the mat above
the membrane, whenever possible, unless
recommended otherwise by the membrane
manufacturer.
Insulation: Insulation dramatically enhances
the performance and efficiency of
floor-warming systems. Do not install rigid
insulation directly above or below backer
board or mortar.
Mosaic Tile: When installing mosaic tile, it is
recommended to apply a two-step process.
First, embed the mat in a thin self-level
mortar bed (1/4”–3/8”), then thin-set the
mosaic tile according to typical practice.
Expansion Joints: Do not install heating mats
through an expansion joint. Install mats
right up to the joint, if necessary, but not
through the joint.
HeatStep™ Mat
Cement backerboard, Cementitious
Underlayment SL-150™, WebCrete®
95, WebCrete® 98 or Ultra Finish™.
Insulation (per International
Residential Code, Chapter 11)
THIN-SET OVER SLAB ON GRADE
Tile/stone or
laminate flooring
Bostik Thin-set or SL-150™
self-leveling mortar bed
HeatStep™ Mat
Crack isolation membrane /Insulating barrier
Concrete slab with
rewire or rebar
!
CAUTION
Never bang a trowel on the Heating
Wire to remove excess mortar from
the trowel. This could damage the
heating wire.
Insulation (per International
Residential Code, Chapter 11)
15
Bostik HeatStep™ Mat Installation Manual
Phase 6: Control Installation
Step 6.1:
Install the Controls
If it has not already been done, install an electrical box for
the HeatStep™ control and HeatStep™ Relay. Do not forget to
attach a single-gang mud-ring to mount the HeatStep™ control if a 4” square box was used. See Phase 3 for details.
Power
supply
electrical box
Step 6.2
Refer to the wiring diagrams in the Appendix of this
manual for typical configurations.
Single-gang Mud Ring
(if required)
Step 6.3
HeatStep™ Thermostat
Read and follow the instructions included with the HeatStep™
thermostat and HeatStep™ Relay for complete connection
instructions, requirements, and mounting.
Electrical conduit
Step 6.4
Make any final connections to the circuit breaker or branch
circuit source.
Sensor wire
Step 6.5
System Start Up
Mat power lead
After all controls are installed, do not energize the system,
except to briefly test operation of all components (no longer
than 10 minutes). Do not put the system into full operation until the tile or flooring installer verifies all cement
materials are fully cured (typically two to four weeks). See
instructions for recommended curing time for the cementitious products used..
Heating Wire
Mat Mesh
Bottom plate
cut-outs
NOTE: Most laminate and wood floor manufacturers
specify their flooring should not be subjected to
temperatures over 820 to 840F (270 to 280C). Check
with the flooring dealer or manufacturer and set the
thermostat Floor Limit temperature appropriately.
Refer to the installation sheets provided with the controls
for proper setting. The system should now operate as
designed. Please leave this instruction manual, HeatStep™
control instructions, and copies of photos of the installed
heating system with the end user.
Place this warning label (provided with the product) on the
electrical panel and indicate the circuit breaker number that
supplies the radiant heating. Also, place the label indicating
“Radiant Floor Heating” on the control.
Radiant Floor Heating Mat
Warning - Risk of electric shock
Electric wiring and heating panels
CKT# contained below the floor. Do not
penetrate floor with nails, screws,
or similar devices
Nappe de chauffage de sol
Avertissement: Rique de choc électrique
Câblage électrique et nappes de chauffage
CKT#
dans le sol. Ne pas enfoncer de clous, vis ou
autes éléments d’assemblage similaires.
Tapete radiante para calefaccion de pisos
Precaución: Riesgo de electrocución
El piso contiene cables eléctricos y paneles
CKT# calafactores. No insertar clavos, tornillos ni
dispositivos similares.
Sensor installed in floor
(equal distance between two heating wires)
Thin-set, thick-set,
thin-slab, or self-leveling
mortar bed
Tile, stone, wood, or
laminate floor covering
General layout of the HeatStep™ Mat installation
16
Bostik HeatStep™ Mat Installation Manual
Appendix
Types of turns
Roll-over Turn
90° or Flip Turn
180° or Back-to-Back Turn
Fill-in Technique
Step-by-step layout for a typical bathroom
1.
2.
3.
4.
5.
6.
7.
8.
Bostik HeatStep™ Mat Installation Manual
Bathroom layout 1:
Control
17
Install mats 6" away from wax ring
(approximately 20") from back wall.
Toilet
Install 4"–6" from walls.
Shower
Install mats right up to the face of the
cabinet. The heat only conducts about
1-1/2" from the wire.
Vanity
Closet
Bathroom layout 2
Install mats 6" away from wax ring
(approximately 20") from back wall.
Bath Tub
Toilet
Locate power lead and factory connection to
heating wire at least 1' outside the shower area.
Do not begin the mat inside the shower area. The
controls should NEVER be installed in the shower
area, or where anyone in the shower could touch
the controls. Install the controls a minimum of 4'
away from the shower area.
Vanity
Tile Thin-set Mortar Shower Curb
Heating Wire
Notches in Shower Curb
(Minimum 1” wide, to avoid sharp
bends in cable and ensure cable is
fully embedded in mortar.)
Shower
Factory Splice
Control
Doorway
Control
Toilet
Never install the mat
in shower walls (or
any other walls).
Bath Tub
Locate power lead and connection
to heating element outside the
shower area.
IMPORTANT
See phase 4 for complete details
and Cautions. This application into
a shower area must be verified by
the local inspector or the authority
having jurisdiction.
Fill in triangular areas by
removing wire from mat and
securing with hot glue..
Doorway
18
Bostik HeatStep™ Mat Installation Manual
Install mats 6" away from wax ring
(approximately 20") from back wall.
Small bath layout 1
Sink
Control
Bath Tub
Front entryway layout
Doorway
Install mats right up to the
face of the vanity. The heat
transfers only about 1-1/2"
from the wire.
Small bath layout 2
Front Entryway
Doorway
Control
Vanity
Bath Tub
Control
Install mats 6" away from wax ring
(approximately 20") from back wall.
Bostik HeatStep™ Mat Installation Manual
120/240VAC Control Wiring Diagrams
Typical Wiring for one
HeatStep™ Mat with
HeatStep™ Control
(120/240VAC)
20-amp circuit.
Ground
Ground
Black
Black
Line 1
LineBlack
1
Black
Sensor Wire
Sensor
Wire
(no polarity)
(no polarity)
120 or 240VAC
120 or 240VAC
White
White
Mat
Mat
(maximum 15 amps)
(maximum 15 amps)
120/240 VAC
120/240 VAC
HeatStep Control
HeatStep Control
Load 1
Load
1
Black
Black
Load 2
Load
2
White
White
Line 2
LineWhite
2
White
Typical Wiring for
multiple HeatStep™ Mats
with HeatStep™ Control
(120/240VAC)
20-amp circuit.
Ground
Ground
120 or 240VAC
120 or 240VAC
White
White
!
Line 1
LineBlack
1
Black
Line 2
LineWhite
2
White
CAUTION
Make sure 120 VAC is supplied
to 120 VAC mats and 240 VAC
is supplied to 240 VAC mats.
Otherwise, dangerous overheating
and possible fire hazard can result.
Note: All electrical work must be done by a qualified licensed
electrician in accordance with local building and electrical codes, and the National Electrical Code (NEC), especially Article 424 of the NEC, ANSI/NFPA70 and Section
62 of CEC Part 1.
Load 2
White
Load
2
White
Sensor Wire
polarity)
(noSensor
Wire
(no polarity)
Black
Black
120/240 VAC
120/240
VAC
HeatStep
Control
HeatStep Load
Control
1
Black
Load
1
Black
Two or more
Two orMats
more
(maximum
Mats 15 amps)
(maximum 15 amps)
19
20
Bostik HeatStep™ Mat Installation Manual
HeatStep™ Relay Connection Diagrams
Ground
Ground
Typical Wiring for
HeatStep™ control with
HeatStep™ Relay(s)
120/240 VAC
Black
Sensor Wire
(no polarity)
20-amp circuit for each HeatStep™
control and HeatStep™ Relay
Load 1Black
Black
Line 1
Line 1 Black
Black
Black
Sensor Wire
(no polarity)
120/240
VAC Control
HeatStep
HeatStep Control
Load 1
120 VAC or 240 VAC
120 VAC or 240
VAC
White
Line 2
White
White
Load 2
White
Line 2
White
Load 2
White
Two or more120 VAC or
240 VAC Heating Mats
Two or more120 VAC or
(maximum 15 amps)
240 VAC Heating Mats
(maximum 15 amps)
Use size 18 to 24 gauge 2 conductor wire
up to 100 feet (30m) in length to connect
HeatStep™ control to HeatStep™ relay.
Ground
Black
Sensor Wire
(no polarity)
120/240 VAC Load 1
Black
HeatStep Relay
Line 1
Load
1
Black
Black
120 VAC or 240Line
VAC1
Black
White
Black
120 VAC or 240 VAC
White
!
Sensor Wire
(no polarity)
120/240 VAC
HeatStep Relay
Ground
Load 2
White
Line 2
White
Two or more120 VAC or
240 VAC Heating Mats
(maximum 15 amps)
Load 2
White
Line 2
White
Two or more120 VAC or
240 VAC Heating Mats
(maximum 15 amps)
CAUTION
Make sure 120 VAC is supplied to 120
VAC mats and 240 VAC is supplied to
240 VAC mats. Otherwise, dangerous
overheating and possible fire hazard
can result.
120/240 VAC
HeatStep Control
120/240 VAC
HeatStep Relay
120/240 VAC
HeatStep Relay
120/240 VAC
HeatStep Relay
Relout
Relin
Relout
Relin
Relin
Relin
Relout
Relout
Setback
Relin
Relout
Relin
Relin
Relout
2
3
4
5
Relin
2
3
4
5
Relin
Relin
Relout
5
Relout
Relout
Setback
Relin
Relout
2
3
4
Sensor
5
Relin
Sensor
Note: All electrical work must be done by
a qualified licensed electrician in
accordance with local building and
electrical codes, and the National
Electrical Code (NEC), especially Article 2
424 of the NEC, ANSI/NFPA70 and Section3
62 of CEC Part 1.
4
Up to 10 HeatStep Relays
can be connected to
one HeatStep Control
Relin
Relin
Relout
Relout
Relin
120/240 VAC
HeatStep Control
120/240 VAC
HeatStep Relay
Relin
Diagram for connection of signal wire
between HeatStep™ Control and Relays
2
3
4
5
2
3
4
5
Up to 10 HeatStep Relays
can be connected to
one HeatStep Control
Bostik HeatStep™ Mat Installation Manual
21
Connecting Multiple Mats
NOTE: The HeatStep™ control is not shown in these diagrams in order to simplify them. These diagrams are given only as examples of how to properly connect multiple mats. Care must be taken not to overfill a box. Be sure to use wire nuts that are the
correct size for the connections being made. Follow all codes for wiring. If in doubt, consult an electrician.
Illustration showing how to connect multiple
mats from multiple junction boxes at
one thermostat control electrical box.
L1 = White
L1 = Red
G = Copper
G = Copper
L2 = Black
L2 = Black
Illustration showing how to connect
three mats at the thermostat control
electrical box.
Connecting the Wire fault detector
Illustrations showing (left) how to connect the
Wire Fault Detector to two cables, and (right)
how to connect the Wire Fault Detector to three
mats. The Wire Fault Detector can monitor no
more than three mats simultaneously. Do NOT
leave the power leads connected in “series” like
this when making final wiring connections; the
cables will not heat sufficiently.
22
Bostik HeatStep™ Mat Installation Manual
Troubleshooting Guide
If problems arise with the HeatStep™ Mat or its related electrical components, please consult this troubleshooting guide. If not qualified to perform electrical work, it is highly recommended a qualified, licensed electrician be hired.
Any electrical troubleshooting work should be performed with the power removed from the circuit, unless otherwise noted.
Although this troubleshooting guide is provided to assist with problems experienced with a HeatStep™ system, results are never
guaranteed. Bostik does not assume any liability or responsibility for damage or injury that may occur from using this guide. If problems with the system persist, call the manufacturer.
Problem
Mat resistance measurement is
outside the range printed on the
nameplate label.
Floor is not getting warm.
Floor heats continuously.
Possible Cause
Solution
An analog meter (using a moving needle) was
used to take the reading.
Obtain a digital multi-meter and re-measure the resistance.
If measurement shows an open or short circuit,
the Heating Wire has been damaged.
Record resistance between all wires and contact the manufacturer.
If measurement is just a little low or high, room
temperature has affected the resistance.
Make the room temperature 75°–85°F (24°-30°C), or contact the manufacturer.
The resistance measurement could be from more
than one mat wired in series, or wired in parallel.
Either will provide false resistance readings.
Make sure resistance measurements are for only one mat at a time.
The multi-meter may be set to the wrong scale.
The multi-meter should typically be set to the 200 ohms (200Ω) scale. For mats with resistance range
higher than 200 ohms on the nameplate label, set the meter to the 2000 ohm (2kΩ) scale.
Mat has been damaged.
Measure mat resistance. Check for both “open circuit” and “short circuit” as detailed earlier in this manual.
If damaged, record resistances between all wires and contact the manufacturer.
GFCI has tripped, indicated by a light or “GFCI
TRIP” on the control.
Check for loose wire connections. Reset the GFCI on the control or circuit breaker. If it trips again, check
for a short circuit in the mat as detailed earlier in this manual. If mat is damaged, record resistance
between all wires and contact the manufacturer. If mat is not damaged, replace the GFCI control. Also
see “GFCI conflicts” below.
Incorrect voltage supplied, or mismatched
electrical components used.
Measure “line” voltage, then measure “load” voltage. 120 VAC mats have black and white power leads.
240 VAC mats have black and blue power leads.
Uninsulated concrete slab floor.
Surface temperatures rise slowly an uninsulated slab and heat is lost to the ground below.. If, after 5 to 8
hours of heating, the floor is not warmer to the touch, check for mat damage (see “Mat has been damaged” above). A clamp-on ampmeter may be used to verify the amps are correct to each mat.
Mats are wired in “series” or “daisy chained”
(end-to-end).
Multiple mats must be connected in “parallel” (or black-to-black, white-to-white).
Incorrect wiring. The control was “bypassed”
when it was wired to the power supply.
Make sure wiring connections are correct. Consult the wiring diagram on the back of the control the
instructions that came with the control, or the wiring diagram in this manual.,
Defective control.
Return control to dealer for replacement.
If a programmable control, the programming may
Carefully read and follow control programming instructions.
be incorrect.
Control is not working correctly.
Control is not working at all.
GFCI conflicts and false-trips
Incorrect voltage supplied, or mismatched
components used.
Test voltage, verify parts. See “Incorrect voltage supplied” above.
Floor sensor is not wired properly, or is not
working properly.
Make sure only one floor sensor is connected to the control. Also see “Sensor is loose or
broken” above.
Loose connection(s) on line side and/or load side
of control.
Remove and reinstall the wire nuts at each connection. Make sure the wire nuts are tight.
Check all connections back to the breaker.
Defective control.
Return control to dealer for replacement.
No power is supplied.
Check circuit breaker. Measure voltage at the control. Check all connections between breaker
and control.
Defective control.
Return control to dealer for replacement.
An electric motor or a ballasted light source is
sharing the circuit with the mat.
Electric motors and other electrical devices can cause a GFCI to false-trip. Run a dedicated circuit
to the floor-warming system or select a different branch circuit..
The manufacturing facility’s Quality
System is an ISO 9001:2008 registered
facility through LRQA.
(800) 7BOSTIK / (800) 726-7845
IOM-BOSTIK-MAT 1233